NICOSIA, Cyprus —The last of Syria’s acknowledged stockpile of chemical weapons has been handed over to Western governments for destruction, the organization charged with overseeing the elimination of such weapons said Monday.

The final 8 percent of the 1,300-ton stockpile, which included mustard gas and raw materials for making sarin nerve gas, have been loaded onto Danish and Norwegian ships in the Syrian port of Latakia, said Ahmet Uzumcu, the director general of the Organization for the Prohibition of Chemical Weapons, also known as OPCW.

Speaking at a press conference in The Hague, however, Uzumcu acknowledged that it is still possible Syria has avoided declaring some part of its arsenal.

“I can’t say … that Syria doesn’t have any chemical weapons anymore,” he said. However, he added that is true of any country that his organization cooperates with, and Syria’s declared arsenal was close to estimates made by external security analysts and experts.

In an interview with The Associated Press in Cyprus, Sigrid Kaag, head of the joint United Nations-OPCW mission in Syria, said her team’s experts “are working closely with the Syrian Republic to look at any discrepancies or any revisions (to Syria’s declaration) that need to take place.”

Syria’s government agreed to surrender its arsenal last fall when the U.S. threatened punitive missile strikes after a chemical attack on a rebel-held suburb of Damascus believed to have killed more than a thousand people.

The Syrian Foreign Ministry said in a statement Monday it had eliminated the chemicals despite difficult security circumstances caused by its ongoing civil war.

It credited the “firm political will of Syrian President Bashar Assad and the initiative of the Russian President Vladimir Putin” to give up the arsenal under the supervision of the U.N. Security Council.

“This significant achievement is further evidence that Syria adheres to its international commitments,” the Syrian statement said.

Uzumcu described Syrian government cooperation as “satisfactory.”

Mission chief Kaag said that although the chemicals won’t be destroyed by an initial June 30 target date, “we’re very pleased with meeting this milestone.”